<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <script>
        // 定义变量
        let score = 71;
        if (score >60 && score < 70) {
            alert("60~70");
        } else if(score > 70 && score <80) {
            alert("70~80");
        } else {
            alert("other...")
        }

    </script>
</head>
<body>

</body>
</html>